1. Field of the Invention
The present invention relates generally to electrical connectors for automotive vehicles. In particular, the present invention relates to a rotary connector that connects a steering wheel of a vehicle and a vehicle body electrically.
2. Description of the Related Art
One such prior art rotary connector is described in, for example, Japanese Patent Publication No. 355955. This rotary connector has a housing body that includes a rotor housing and a stator housing. The housing body houses a spiraled flat cable that makes electrical connection between a vehicle body and a steering wheel. The housing body houses a spiraled flat cable that makes electrical connection between a vehicle body and a steering wheel. Such a connector is used for an air bag system or an alarm system that is provided to a steering wheel. Because the flat cable carries small currents, the flat cable is of the construction in which thin wires are covered with a film material. The flat cable of the prior art rotary connector functions sufficiently for carrying small currents.
Recently, some steering wheels have a heater, which requires a large current. If the aforementioned flat cable is used for supplying a current to a handle heater, there is a possibility that the wires of the flat cable generate too much heat and melt the film material covering the wires. Therefore, the wires of the flat cable are not capable of carrying a large current, and the flat cable is unsuitable for a handle heater.
In view of this problem, the applicant of the present invention has proposed a structure disclosed in Japanese Patent Laid-Open No. 2001-196145. This structure includes a flat cable and an additional cord for carrying a large current for a handle heater. This structure uses a flat cable for supplying small currents to, for example, an air bag and an alarm, and a large-current cord for supplying a large current to the handle heater.
However, the aforementioned large-current cord runs through a shaft sleeve inserted into a steering shaft and is connected to a power supply through a slip ring mechanism outside of the stationary stator housing. To accommodate the large-current cord and slip ring mechanism, a special space is required in the shaft sleeve and outside of the stator housing. Thus, the overall height of the apparatus increases by the height of the slip ring mechanism, making the apparatus large in size.
In addition, because the cord runs in the shaft sleeve, there is a possibility that the cord contacts a steering shaft to rub the steering wheel. Also, since the slip ring mechanism is provided outside of the stator housing, the sounds created by the slip ring mechanism may leak to the outside and cause abnormal sounds.
In rotary connectors used for automobiles, a large number of switches are arranged in the pads and spoke of the steering wheel, and a large number of wires are required for making electrical connection between the switches and the vehicle body. However, because various devices are mounted around the steering wheel, the axial height of the flat cable having wires therein and the height of a rotary connector have to be designed to a specific value. This limits the number of wires that can be included in the flat cable, e.g., several wires.
Some rotary connectors have a plurality of flat cables in order to solve this problem. However, the number of flat cables is limited only to two or three due to a limited space for mounting terminals to which the opposed ends of the flat cables are fixed.
A first object of the present invention is to provide a rotary connector that allows increasing the number of electrical paths that connect the vehicle body and the steering wheel while still maintaining the overall size as small as possible.
A second object of the invention is to provide a rotary connector that has a large-current path in addition to the flat cable while still maintaining the overall size of the rotary connector as small as possible.
A third object is to provide a rotary connector that prevents occurrence of abnormal sounds.
To accomplish these and other objects of the invention, a rotary connector is provided having a stationary member supported on a body side of an automobile; a rotative member rotatably supported on the stationary member, the rotative member being rotatable together with a steering wheel; a floating spacer disposed between the stationary member and the rotative member and having a gap that extends in a radial direction of the floating spacer so that an inner space of the floating spacer communicates with an outer space of the floating spacer through the gap, the floating spacer being pivotal when the rotative member rotates; and a flat cable having one end that is supported on the stationary member and connected to a power supply side, the other end that is supported on the rotative member and connected to an electrical apparatus on the steering wheel side, and a mid folding portion that passes through the gap in a floating spacer to fold back so that the flat cable is wound around the outer surface and the inner surface of the floating spacer, the flat cable lying between the stationary member and the rotative member.
The rotary connector has a slip ring mechanism, comprising: a stationary contact provided on the stationary member, the stationary contact being connected to the power supply and opposing the floating spacer so that the stationary contact extends along a pivotal path of the floating spacer; a movable contact provided on the rotative member, the movable contact being connected to an electrical apparatus on the steering wheel side and opposing the floating spacer so that the movable contact extends along a pivotal path of the floating spacer; and a floating contact provided to the floating spacer which is electrically connected to the stationary contact and the movable contact.
According to another aspect of the present invention, the rotary connector further comprises an annular stationary contact provided on the stationary member, the annular stationary contact being connected to the power supply and opposing the floating spacer to extend along the pivotal path of the floating spacer; an annular movable contact provided on the rotative member, the annular movable contact being connected to the electrical apparatus on the steering wheel side and opposing the floating spacer to extend along the pivotal path of the floating spacer; and a floating contact provided to the floating spacer which is in resilient contact with the stationary contact and the movable contact.
According to another aspect of the present invention, the rotary connector further comprises a contact-receiving recess formed in the floating spacer and receiving the floating contact therein and exposing two opposed ends of the floating contact to the stationary contact and the movable contact. The floating contact is received in the contact receiving recess.
According to yet another aspect of the present invention, the floating contact has contacts on its opposed two ends thereof and an electrically conductive spring that makes the contacts electrically continuous with each other and makes the floating contact in resilient contact with the stationary contact and the movable contact.
Numerous other objects of the present invention will be apparent to those skilled in this art from the following description wherein there is shown and described an embodiment of the present invention, simply by way of illustration of one of the modes best suited to carry out the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various obvious aspects without departing from the invention. Accordingly, the drawings and description should be regarded as illustrative in nature and not restrictive.